1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device and a forming method of the plate electrodes thereof, and more specifically, to an LCD device and a forming method of the plate electrodes, utilizing forming a corresponding couple capacitor in a sub-pixel unit to adjust the voltage on the electrode plates for correcting the voltage-transmittance characteristic curve (V-T curve) of the sub-pixel unit, resulting in the elimination of color tracking effects.
2. Description of the Prior Art
In a liquid crystal display (LCD) device, the transmittance of the liquid crystal panel is determined in accordance with the polar vector of light that is controlled via an upper polarizer, a lower polarizer, and a liquid crystal layer. Because of physical characteristics of the liquid crystal, when light passes through the liquid crystal layer, the phase of the light is delayed, so the direction of polarization of the light is variant, and results in different transmittance. This means that when a fixed voltage is applied on two sides of the liquid crystal layer, light with different wavelengths corresponds to different transmittance after passing through the liquid crystal layer and the polarizers.
For a vertical aligned LCD device, the voltage-transmittance characteristic curve (V-T curve) is different with different wavelengths of light; therefore, for trichromatic colors R, G, and B, the corresponding V-T curves are different. Consequently, when the voltage between two sides of the liquid crystal layer is adjusted to regulate the gray-level value of the LCD device, due to the V-T curves of trichromatic colors R, G, and B being different, the mixing ratio of the trichromatic colors R, G, and B is also different, resulting in the named color tracking effect.
Please refer to FIG. 1. FIG. 1 is a voltage-transmittance characteristic curve of trichromatic colors R, G, and B in a vertical aligned liquid crystal display device according to the prior art. The horizontal axis represents the voltage applied across the liquid crystal layer, the vertical axis represents normalized transmittance, and the V-T curves 10, 15, 20 correspond to blue light, green light, and red light respectively. As shown in FIG. 1, when the voltage between two sides of the liquid crystal layer is from 2 volts to 6 volts, the transmittance of blue, green, and red light is different, causing the color tracking effect. For example, if the voltage applied across two sides of the liquid crystal layer is 5.5 volts, the ratio of transmittance for red, green, and red light is approximately 1:1:1, and a pure white light is obtained. However, if the voltage applied across two sides of the liquid crystal layer is reduced to 3 volts, the brightness is decreased, and the ratio of transmittance for red, green, and red light becomes 7:7:12 approximately, therefore the original pure white light turns a little blue. As described above, the color tracking effect reduces display performance of related, vertical aligned LCD devices.